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Technical Note 420

BLM/ST/ST-06/003+3720
Phytostabilization as a Remediation Alternative at Mining Sites

Technical Note 420

By:

Dennis Neuman 

Reclamation Research Unit

Montana State University

and

Karl L. Ford

National Science and Technology Center

Bureau of Land Management

December 2006
Suggested citation:

Neuman, D. and K.L. Ford. 2006. Phytostabilization as a remediation alternative at mining sites. 

Technical Note 420. BLM/ST/ST-06/003+3720. Bureau of Land Management, Denver, CO. 48 pp. 

Online at www.blm.gov/nstc/library/techno2.htm.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

iii

Table of Contents

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 What is Phytostabilization? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Application to Mining Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.3 Phytostabilization Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.0 Study Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.1 Plot Setup and Soil/Tailings Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.2 Analytical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3.0 Research Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.1 General Comments Regarding the Site in July 2005 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.2 Canopy Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.3 Species List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.4 Aboveground Biomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.5 Metal Levels in Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.0 Future Directions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

5.0 References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Appendix A–Site Photos from July 2005 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Appendix B–Canopy Cover of Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Appendix C–Aboveground Biomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Appendix D–Arsenic and Metal Levels in Vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

iv

List of Figures

Figure 1. Vegetation around the margins of the Keating tailings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Figure 2. Schematic of onsite experimental plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 3. Schematic of offsite experimental plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 4. Mean aboveground biomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 5. Mean concentrations of arsenic, cadmium, and lead in grass samples . . . . . . . . . . . . . . . . 17

Figure 6. Mean concentrations of copper and zinc in grass samples . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure A-1. Overview of experimental plots on Keating tailings, July 6, 2005 . . . . . . . . . . . . . . . . . . . . 23

Figure A-2. The treated tailings plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure A-3. A treated plot with yarrow in flower along the plot edge and the stand

dominated by the seeded wheatgrasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure A-4. Untreated (control) tailings plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Figure A-5. Offsite experimental plots on native soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure A-6. Treated tailings pit face and roots sprayed with Hellige pH indicator

solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure A-7. Untreated (control) tailings pit face and roots sprayed with Hellige pH 

indicator solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

List of Tables

Table 1. Soil and tailings analytical methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Table 2. Tailings and soil metal levels determined by Ashe Analytics using a

laboratory-grade XRF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Table 3. Water extractable metal (saturated paste extract) determined by ICP

at Montana State University Soil Testing Laboratory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Table 4. Cations and other physicochemical results from Montana State University

Soil Testing Laboratory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Table 5 Comparison of perennial grass and forb canopy cover on the

Experimental plots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Table 6. Species occurring on each experimental plot of the Keating tailings

project, 2005 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Table B-1. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 1: Offsite native range site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Table B-2. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 2: Offsite native range site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Table B-3. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 3: Offsite native range site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Table B-4. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 4: Offsite native range site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Table B-5. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 5: Onsite treated with lime and organic matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Table B-6. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 6: Onsite treated with lime and organic matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Table B-7. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 7: Onsite control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Table B-8. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 8: Onsite control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Table B-9. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 9: Onsite treated with lime and organic matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Table B-10. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 10: Onsite control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Table B-11. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 11: Onsite treated with lime and organic matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

vi

Table B-12. Vegetation cover at Keating tailings, July 7, 2005 – 

Plot 12: Onsite control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Table C-1. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 1: Offsite native range site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Table C-2. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 2: Offsite native range site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Table C-3. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 3: Offsite native range site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Table C-4. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 4: Offsite native range site. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Table C-5. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 5: Onsite treated with lime and organic matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Table C-6. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 6: Onsite treated with lime and organic matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Table C-7. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 7: Onsite control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Table C-8. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 8: Onsite control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Table C-9. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 9: Onsite treated with lime and organic matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Table C-10. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 10: Onsite control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Table C-11. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 11: Onsite treated with lime and organic matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Table C-12. Aboveground biomass vegetation at Keating tailings, July 7, 2005–

Plot 12: Onsite control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Table D-1. Arsenic and metal levels (mg/kg) in vegetation collected from experimental 

plots at Keating tailings, July 7, 2005 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

vii

Abstract

In the last 10 years, the Bureau of Land Management (BLM) has reclaimed a number of abandoned 

mine land (AML) sites, often by removing mine, 

mill, and smelter wastes and taking them to a repository. This removal process involves excavating, 

hauling, placing, and capping tens of thousands of 

cubic yards of material, which can be quite costly.

BLM is seeking more cost-effective methods for 

reclaiming AML sites. Phytostabilization is a 

promising alternative for accomplishing the goals 

of a removal at a tenth of the cost. Phytostabilization is an in situ technology involving soil amendments and metals-tolerant plants to establish a 

ground cover that can reduce migration of metals 

to air, surface water, and ground water; reduce soil 

toxicity; and meet applicable, relevant, and appropriate requirements (ARARs). This technology has 

been found effective under certain conditions.

Through a 3-year applications of science (AOS) 

grant, BLM’s National Science and Technology 

Center (NSTC) has worked with field offices and 

universities to pilot phytostabilization at two sites. 

This Technical Note summarizes the work done at 

the Keating tailings site near Butte, Montana, by 

Montana State University.

At the Keating tailings site, planting occurred 

in 2003. This year, which was the last year of 

the AOS grant, the test plots were in their third 

growing season. Canopy cover and aboveground 

biomass data have been collected, and samples 

have been analyzed for metal and arsenic concentrations. However, at least 1-2 years of additional 

monitoring of plant establishment and metals 

uptake sampling are required to verify the success 

of the technology and determine its feasibility for 

other AML sites on public lands.

Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420



1.0 Introduction

The public lands managed by the Bureau of Land 

Management (BLM) contain a large number of 

abandoned mine land (AML) sites, many of 

which are releasing contaminants, threatening 

human health and the environment, or violating 

environmental laws. BLM’s Abandoned Mine 

Lands Inventory System (AMLIS) lists over 

9,400 AML sites, most of which are from historic 

mining operations.

Active mine sites are being abandoned with 

greater frequency due to bankruptcy. These sites 

range from less than an acre to hundreds of acres. 

Abandoned sites differ from sites where active 

mines were closed in that they have no onsite 

presence and often no preclosure planning work 

was completed for them. Consequently, structures 

such as impoundments and dams have failed at 

these sites.

Research and demonstrations are needed to 

develop more cost-effective technologies appropriate 

for reclaiming BLM’s AML sites. Phytostabilization 

is one such technology that shows promise 

(EPA 2000).

1.1 What is Phytostabilization?

Phytostabilization is the use of metals- tolerant 

plants to inhibit the mobility of metals, thus reducing the risk of further environmental degradation by leaching into ground water or by airborne 

spread (Salt et al. 1995). During phytostabilization, 

metals are chemically precipitated or sequestered 

by complexation and sorption mechanisms within 

the tailings or soils. Metal availability to plants is 

minimized, and metal leaching into ground water 

is reduced. Metals and arsenic that remain in soil 

solutions are demobilized via chemical reactions at 

plant root surfaces.

Plant species serve several purposes in phytostabilization. Plants harvest water in the rootzone and 

can transpire several hundred thousand gallons of 

water per acre during the growing season. This 

harvest has a significant impact on the volume of 

water (and metals and arsenic) that is able to move 

towards the ground water. Plants stabilize the 

landscape from erosion, greatly reducing surface 

water runoff and sediment available to receiving 

streams. Plants also reduce erosion caused by 

wind. Plant species are selected for phytostabilization based on the availability of their seeds or 

seedlings, their ability to thrive in the newly created rootzone, their lack of ability to translocate 

(or move) metals and arsenic from the roots into 

the aboveground biomass of the plant, and land 

use and management considerations.

There is a significant body of literature showing 

that phytostabilization is feasible under certain 

conditions. Phytostabilization has been found 

suitable for:

• Upland sites out of the flood plain

• Sites without shallow ground water

• Sites with low to moderate soil metals 

concentrations (as a point of departure 

depending on various factors: <1,500 ppm 

Cu+Pb+Zn+As+Cd+Hg)

• Repository sites, in place of an engineered cap

• As a partial component of a removal action 

involving several remedies, including repositories 

or capping

1.2 Application to Mining Sites

Environmental impacts at AML sites are highly 

variable, but many are characterized by high concentrations of toxic metals, cyanide, and acidity in 

mining waste that is released into surface water, 

ground water, and soils. The typical scenario is 

that tailings from historic mining operations reside 

in old, breached impoundments. Sometimes there 

are tolerant plant colonists established on tailings 

interspersed with bare tailings (called sickens), but 

frequently the tailings are devoid of vegetation. 

Bare tailings are available to release metals into 

the air as dust, into surface water by erosion and 

leaching, and into ground water by leaching. Bare 

tailings are not only toxic to plants, but also to fish 
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420



and wildlife; thus, they represent a loss of habitat. 

Such sites may not comply with Federal and State 

environmental laws regulating air, water, and soil 

pollution and may be subject to enforcement.

Current cleanup methods usually involve removing 

and transporting contaminated materials to a 

disposal facility or isolating the mine wastes by 

capping them with clean fill. Both technologies 

are very expensive. For example, assume a 

repository action for a small 1-acre site with 

10,000 cubic yards at a unit cost of $30-$100 per 

cubic yard. After removal, both the cleaned 

area and the repository need reclamation. 

The minimum cost under this scenario is 

$300,000-$1,000,000, not counting design, construction oversight, and other costs. Cleanup costs 

can range from $10,000 to $8 million per site.

Funding priority has been given to sites with 

tailings and rock dumps situated in stream channels 

and to sites that present significant human or 

ecological risk. Usually these sites are located on 

public lands used for recreation, grazing, wildlife, 

and water resources. Often these sites are remote 

from power and roads and may have restrictions 

because of designations of cultural resources, 

wilderness, or national conservation areas 

(e.g., San Pedro River).

Annual funding of $10 million is grossly inadequate to address the cleanup cost burden using 

current technologies. High-technology cleanup 

solutions employed by the Environmental Protection Agency (EPA) at Superfund sites are often not 

practical for remote, resource limited BLM sites. 

Cleanup costs for a single complex site can consume the entire annual budget. At present funding 

levels, it will take many years to clean up AML 

sites. It is very important, therefore, that lower 

cost cleanup alternatives be found for AML sites 

or their contaminants may end up polluting the 

environment for hundreds of years.

1.3 Phytostabilization Study

Through an Applications of Science (AOS) grant, 

the BLM and Montana State University’s (MSU’s) 

Reclamation Research Unit (RRU) have undertaken a study to investigate the use of phytostabilization to remediate the Keating tailings site 

near Butte, Montana. The objective of the study 

is to provide BLM managers and decisionmakers 

with site-specific information and data relating to 

the implementation, costs, and effectiveness of 

this technology so that it may be applied to other 

similar acid metalliferous mine tailing sites administered by the BLM. This work has been summarized in papers at the Environmental Protection 

Agency’s (EPA’s) International Phytotechnologies 

Conference in Atlanta in 2005, the National 

Association of Abandoned Mine Land Programs 

Annual Conference in Flagstaff in 2004 (Ford and 

Neuman 2004), and at the American Society of 

Mine Reclamation meeting in Breckenridge in 

June 2005 (Neuman et al. 2005).

AML sites have had the benefit of years of natural 

attenuation or restoration and, as such, are ideal 

laboratories to study the ecological effects of metals on plant communities and how to revegetate 

or phytostabilize tailings with plants. At present, 

literature on plant toxicity and plant tolerance is 

limited to agricultural crops and nonnative grasses. 

Little quantitative information is available for western range grasses, shrubs, and trees. This study 

employs public lands as a laboratory to examine 

the effects of metals toxicity on range plants.

Knowledge of plant toxicity to range plant communities typical of public lands is needed to determine whether, and under what conditions, soils 

and mining waste can be revegetated. Plant toxicity 

is also a function of acidity (often contributed by 

mine tailings) and other soil properties, such as 

organic matter and buffering capacity. Some mine 

waste is so toxic or acidic that it will require soil 
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420



amendments to grow plants. This study addresses 

these issues as well as other questions concerning 

the extent to which plants will accumulate metals 

into their tissues and be available to the food chain 

and wildlife.

Knowing which native plants are tolerant to metals 

toxicity and how tailings may be amended to support plant species will lead to more cost-effective 

mine reclamation and restoration decisions. This 

crucial information may save scarce remediation 

and restoration dollars if amendments can be 

found to enable revegetation of mine tailings.

This study evaluates the ability of range plants 

to tolerate toxicity and adverse soil properties. In 

addition, it investigates the utility of inexpensive, 

locally available soil amendments in reclaiming old 

tailings and mine wastes, including waste manure 

from BLM wild horse and burro facilities, if available. Studying BLM sites with representative range 

plants and associated ecological conditions will 

lead to more cost-effective reclamations at AML 

sites, thus maximizing the benefit realized per 

dollar expended.

Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420



2.0 Study Design

The Keating tailings site is located in Broadwater 

County, Montana, on land administered by the 

BLM. These low pH (4 standard units or su) 

wastes resulting from historic gold and copper 

mining operations contain phytotoxic levels of several metals and are generally devoid of vegetation 

(Figure 1). With an estimated volume of 

110,100 m3, these tailings represent an unacceptable 

risk to the environment and human health.

plants seeded into tailings that are not amended 

and plants seeded in an adjacent offsite, but nonimpacted, area. This study design is intended to 

satisfy management and project objectives stated 

in the RRU statement of work (SOW) (RRU 2003) 

and in this Technical Note.

The research is being conducted in two phases. 

Phase I is the implementation of the experimental 

design at the Keating tailings. Phase II is the monitoring of vegetation responses and basic tailings 

chemistry as affected by phytostabilization. This 

Technical Note is a report 

of completed phase I 

activities and preliminary 

phase II findings.

2.1 Plot Setup 

and Soil/Tailings 

Sampling

Onsite and offsite study 

plots were surveyed and 

staked, with the perimeter corners of the test 

areas located using a 

Garmin IV Plus global 

positioning system (GPS) 

unit (Figures 2 and 3). 

Tailings and soil samples 

were collected from each 

of the plots using a Giddings soil probe. Three 

subsamples from each onsite plot were collected 

at 0- to 46-cm (0- to 18-in) increments and composited. In addition, three composite tailing samples 

were collected from 0 to 15 cm (0 to 6 in) and 

placed in new poly bags. Soil samples (0 to 15 cm) 

were also collected from the offsite plots using 

the Giddings soil probe. The samples were transported to the RRU at Montana State University, 

where they were dried and sieved to the < 2 mm 

fraction. These samples were characterized for 

several physicochemical parameters (Table 1).

The study design involved constructing replicated 

experimental plots using soil amendments chosen 

to ameliorate the plant-inhibiting chemical characteristics of the tailings; seeding the experimental 

plots with appropriate native plants that can thrive 

in the newly created rootzone; monitoring vegetation response variables (specifically establishment, 

seedling density, cover, and aboveground biomass); 

and determining tailings pH, soil conductivity 

(SC), and soluble metal levels before and after 

treatment. The study compares the performance 

of vegetation grown in the amended or 

phytostabilized tailings to the performance of 

Figure 1. Vegetation around the margins of the Keating tailings.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420



N

Plot 12-onsite

control (no

amendments)

Plot 10-onsite

control (no

amendments)

Plot 9-onsite

treated

3 m (10 ft)

6 m (20 ft)

Plot 11-onsite

treated

Plot 8-onsite

control (no

amendments)

Plot 6-onsite

treated

Plot 5-onsite

treated

Plot 7-onsite

control (no

amendments)

27.4 m (90 ft)

Perimeter Fence

27.4 m (90 ft)

Figure 2. Schematic of onsite experimental plots.

N

Plot 4-offsitePlot 2-offsitePlot 1-offsite

3 m (10 ft)

Plot 3-offsite

6 m (20 ft)

12.2 m (40 ft)

27.4 m (90 ft)

Perimeter Fence

Figure 3. Schematic of offsite experimental plots.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420



2.2 Analytical Results

Soil and tailing metal levels were analyzed by Ashe 

Analytics using an x-ray fluorescence (XRF) device 

(Table 2). The Niton XRF device has both cadmium 

and americium source materials. The samples 

were analyzed for arsenic (As), cadmium (Cd), 

copper (Cu), mercury (Hg), manganese (Mn), lead 

(Pb), and zinc (Zn). Water extractable metal levels 

were determined from saturated paste extracts 

by the Soil Testing Laboratory at Montana State 

University (Table 3). The extracts were filtered 

and acidified, then analyzed using an inductively 

coupled atomic emission spectrophotometer 

calibrated for the metals analyzed.

Total As values determined by Ashe Analytics 

ranged from 30.4 mg/kg for soils collected from 

the offsite study area to a maximum of 334 mg/kg 

on plot 11. Background As values ranged from 

1.2 to 97 mg/kg for 490 soil samples in the Western 

U.S. (Munshower 1994). Adriano (1986) lists 

background As values in normal soils from 0.2 to 

40 mg/kg. Water extractable arsenic levels ranged 

from 0.43 to 0.84 mg/kg. Munshower (1994) 

reports water extractable arsenic levels in normal 

soils at “presumably” less than 1 mg/kg. Arsenic 

is more toxic to animals than plants, but can be 

phytotoxic when plant tissue levels increase up to 

20 mg/kg (Munshower 1994).

The maximum total Cd value from Ashe Analytics 

was 5.3 mg/kg for a composite sample collected 

from plot 10 on the tailings site. Water extractable 

Cd levels were up to 6.26 mg/kg in the plot 12 soil 

composite. Total background levels for Cd in soils 

is less than 3 mg/kg (Munshower 1994) with an 

average of 1.6 mg/kg for alluvial soils (Adriano 

1986). Phytotoxicity responses to Cd have been 

noted in values as low as 0.5 mg/kg added to 

solution, with responses in tall fescue and alfalfa 

ranging from 95 to 30 mg/kg added to soil 

(Adriano 1986).

CONSTITUENTS METHOD

Soil Preparation Separation for analysis of ≤ 2 mm 

fraction

ASTM D421-85 (ASTM 1997)

Percent Rock Fragments Dry sieve analysis of rock fragments 

(> 2 mm) by volume and mass

ASTM D422-631 (ASTM 1997)

Particle Size, Soil Textural Class Hydrometer method for soil texture, 

USDA classification

ASA Method 15-5 (ASA 1986)

Saturation Percent Saturation percent by weight of 

water to soil

ASA Method 21-2.2.2 (ASA 1986)

Sodium Adsorption Ratio Soil fraction Method 3.2.19 (Sobek et al. 1978)

Electrical Conductivity Saturated paste extract USDA Handbook 60, Method 3a, 4b (U.S. Salinity 

Lab Staff 1969)

pH Saturated paste extract USDA Handbook 60, Method 3a, 21c (U.S. Salinity 

Lab Staff 1969)

Total As and Metals, Soluble As 

and Metals

As, Cd, Cu, Pb, Hg, Co, Cr, Fe, Mn, Ni, 

and Zn

Standard EPA CLP methods (www.epa.gov/superfund/programs/clp) for soluble metals in saturated 

paste extracts. Total metals by BLM using x-ray 

fluorescence methods.

K Fertilizer requirement Method 13-3.5 (ASA 1982)

NO3-N, NH4-N Fertilizer requirement Method 4500 F, H (APHA 1989)

P Fertilizer requirement Bray -P, Method 24-5.1 (ASA 1982)

Total Organic Matter Based on organic carbon Method 29-3.5.2 (ASA 1982)

1 Modifications to ASTM D422-63 include volumetric determination of the percent retained on the No. 10 sieve. The set of sieves specified in ASTM D422-63 

reduced to only the No. 10 sieve and any larger mesh sieves necessary for optimum laboratory efficiency.

Table 1. Soil and tailings analytical methods.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420



Sample 

ID

Plot No. 

Depth

As

(mg/kg)

Cd

(mg/kg)

Cu

(mg/kg)

Hg

(mg/kg)

Mn

(mg/kg)

Pb

(mg/kg)

Zn

(mg/kg)

1 Plot 1

(offsite)

0-6”

30.7 <4.2 43.8 <7.5 1140.0 30.4 105.0

2 Plot 2

(offsite)

0-6”

33.2 <4.2 42.3 <7.5 1090.0 31.1 110.0

3 Plot 3

(offsite)

0-6”

30.4 <4.2 50.7 <7.5 1080.0 30.3 114.0

4 Plot 4

(offsite)

0-6”

30.7 <4.2 46.0 <7.5 1140.0 26.8 101.0

5 Plot 5

(onsite treated)

0-18”

26.0 <4.2 281.0 <7.5 637.0 181.0 611.0

6 Plot 6

(onsite treated)

0-18”

279.0 <4.2 300.0 <7.5 1180.0 271.0 870.0

7 Plot 7

(onsite control)

0-18”

276.0 <4.2 329.0 <7.5 1130.0 258.0 924.0

8 Plot 8

(onsite control)

0-18”

274.0 4.5 327.0 <7.5 1570.0 256.0 1110.0

9 Plot 9

(onsite treated)

0-18”

312.0 4.4 414.0 <7.5 1360.0 323.0 1170.0

10 Plot 10

(onsite control)

0-18”

305.0 5.3 356.0 <7.5 1480.0 289.0 1170.0

11 Plot 11

(onsite treated)

0-18”

334.0 <4.2 358.0 <7.5 1380.0 273.0 1170.0

12 Plot 12

(onsite control)

0-18”

310.0 <4.2 341.0 <7.5 1340.0 233.0 1020.0

13 Plot 11

Duplicate

322.0 <4.2 344.0 <7.5 1420.0 287.0 1210.0

14 2710 NIST*

Standard

621.0 21.8 2990.0 31.2 10000.0 5520.0 6940.0

Table 2. Tailings and soil metal levels determined by Ashe Analytics using a laboratory-grade XRF.

Samples collected on July 9, 2003.

* National Institute of Standards and Technology
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420



Sample 

ID

Plot 

No. 

Depth

As 

(mg/kg)

Cd 

(mg/kg)

Co 

(mg/kg)

Cr

(mg/kg)

Cu 

(mg/kg)

Fe

(mg/kg)

Mg 

(mg/kg)

Mn 

(mg/kg)

Ni

(mg/kg)

Pb 

(mg/kg)

Zn 

(mg/kg)

1 Plot 1 

(offsite)

0-6”

0.66 <0.03 <0.07 <0.08 0.07 <0.17 93.69 0.21 <0.07 <0.28 <0.03

2 Plot 2 

(offsite)

0-6”

0.68 <0.04 <0.07 <0.08 0.08 <0.17 76.00 0.24 <0.07 <0.28 <0.03

3 Plot 3 

(offsite)

0-6”

0.77 <0.05 <0.07 <0.08 0.09 <0.17 90.00 0.23 <0.07 <0.28 <0.03

4 Plot 4 

(offsite)

0-6”

0.43 <0.06 <0.07 <0.08 0.06 <0.17 52.00 0.23 <0.07 <0.28 <0.03

5 Plot 5 

(onsite 

treated)

0-18”

0.47 0.68 0.84 0.52 2.40 <0.17 2358.00 183.00 1.83 <0.28 51.60

6 Plot 6 

(onsite 

treated)

0-18”

0.62 2.64 1.29 0.62 33.80 0.39 2637.00 325.00 2.97 0.56 135.00

7 Plot 7 

(onsite 

control)

0-18”

0.61 3.45 1.56 0.74 28.90 0.54 3114.00 363.00 3.79 <0.28 202.00

8 Plot 8 

(onsite 

control) 

0-18”

0.61 4.91 1.84 0.75 10.60 0.61 2864.00 665.00 5.39 0.61 269.00

9 Plot 9 

(onsite 

treated) 

0-18”

0.79 6.18 4.03 0.86 62.40 0.93 2732.00 960.00 8.99 0.93 398.00

10 Plot 10 

(onsite 

control) 

0-18”

0.72 5.51 2.36 0.86 31.20 0.86 3079.00 871.00 7.73 0.79 338.00

11 Plot 11 

(onsite 

treated) 

0-18”

0.74 6.19 3.46 0.74 47.80 1.03 2580.00 727.00 7.37 0.88 390.00

12 Plot 12 

(onsite 

control) 

0-18”

0.84 6.26 3.87 0.91 51.50 1.05 3374.00 1003.00 9.63 0.91 433.00

13 Plot 11 

Duplicate

0.73 5.53 2.98 0.95 33.50 1.02 2690.00 694.00 7.27 0.87 385.00

Table 3. Water extractable metal (saturated paste extract) determined by inductively coupled plasma (ICP) at 

Montana State University Soil Testing Laboratory. Samples collected on July 9, 2003.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

10

Copper values ranged from 42.3 mg/kg in the 

offsite control soils to 358 mg/kg in tailings from 

plot 11 compared to typical background soil values 

of 3 to 50 mg/kg (Munshower 1994). Phytotoxic 

effects have been noted in soils with a pH greater 

than 6.5 for total soil Cu values in the range of 

1062-1636 mg/kg (USEPA and MDEQ 1998). 

Water extractable values ranged from 0.06 to 

62.4 mg/kg. Using the water extractable fraction 

of Cu in the soil as a conservative estimate of 

the labile portion available to plants, yields have 

been reduced in plants such as spring wheat, sugar 

beets, and maize above 2 mg/kg Cu in solution 

(Adriano 1986).

Manganese levels in the tailings and soil ranged 

from 637 to 1570 mg/kg for total values. Water 

extractable levels, which are presumably labile to 

plants, ranged from 0.21 mg/kg for the offsite soils 

to a maximum of 1003 mg/kg for plot 12 on the 

tailings site. Manganese toxicity to plants generally 

occurs when soil pH levels are less than 5.5 (Adriano 

1986). Water extractable levels of Mn at 2.5 mg/kg 

in soils with pH of <5.5 have been found to be toxic 

to plants (Munshower 1994). The low pH values 

in the tailings (< 5.6) and high Mn values are well 

within this phytotoxic range (Table 4).

Zinc levels determined by Ashe Analytics were 

elevated (611-1210 mg/kg) in the tailings material 

compared to the offsite control soils (101-114 mg/kg).

Water extractable values were <0.03 in the offsite 

soils and ranged from 51.6 to 433 mg/kg in the 

tailings material. Zinc is a required plant nutrient, 

but phytotoxic response has been shown with 

DTPA extractable values from 50 to 150 mg/kg 

(Munshower 1994). Adriano (1986) reported phytotoxic effects in corn in acid soils from extractable 

Zn values of 450 to 1400 mg/kg.

Soil pH, texture, percent organic matter, and other 

physicochemical analytical results vary widely 

between the offsite soils and the tailings material 

(Table 4). Tailings pH values are all below the 

desired range of 6.5 to 8.5 su, while the offsite control soils are all near 8.5 su. The tailings material 

textures are all classified as silt loam or silt, while 

the offsite soils range from sandy clay loam to clay 

loam. A comparison with cover soil criteria for the 

Anaconda area (U.S. EPA and MDEQ 1998) shows 

that many of the tailings samples exceed the upper 

limit for conductivity of 4.0 dS/m and have very 

little organic matter All of the sodium absorption 

ratio (SAR) values are less than 4, indicating that 

the tailings and offsite soils are within the “normal” 

soil range (Sobek et al. 2000). Rock content was 

less than 1 percent for all samples.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

11

Sample 

ID

Plot No. 

Depth

Na 

(mg/L)

Ca 

(mg/L)

pH SAR Conduct. 

(dS/m)

H2O 

(%) sat. 

paste

Sand 

(%)

Silt (%) Clay 

(%)

USDA 

Texture

Organic 

Matter 

(%)

NO3 as 

N (mg/

kg)

Olson P 

(mg/kg)

K (mg/L)

1 Plot 1 

(offsite)0-6”

39 79 8.5 1.0 0.71 34.7 50 24 26 sandy clay 

loam

2.19 0.8 12.9 342

2 Plot 2

(offsite)0-6”

13 98 8.4 0.3 0.66 40.2 54 24 22 sandy clay 

loam

2.60 0.9 13.9 356

3 Plot 3 

(offsite)0-6”

113 33 8.5 3.8 0.74 45.2 42 22 36 clay loam 1.90 0.8 11.8 276

4 Plot 4 

(offsite)0-6”

109 30 8.5 3.9 0.70 28.8 56 24 20 sandy clay 

loam

1.56 0.5 10.6 228

5 Plot 5 

(onsite treated)0-18”

55 506 5.6 0.4 3.81 52.4 18 76 6 silt loam 0.23 2.9 40.1 172

6 Plot 6 

(onsite treated)0-18”

77 497 4.2 0.6 4.18 56.1 16 78 6 silt loam 0.17 6.9 38.8 134

7 Plot 7 

(onsite control)0-18”

85 496 4.1 0.7 4.24 67.7 12 84 4 silt 0.22 5.8 35.1 168

8 Plot 8 

(onsite control)0-18”

164 497 4.5 1.3 4.30 68.2 8 88 4 silt 0.19 8.9 36.0 150

9 Plot 9 

(onsite treated)0-18”

102 538 4.2 0.8 4.26 71.9 4 90 6 silt 0.09 71.1 33.3 124

10 Plot 10 

(onsite control)0-18”

115 516 4.3 0.9 4.36 71.6 7 88 5 silt 0.19 38.5 28.3 146

11 Plot 11 

(onsite treated)0-18”

90 508 4.2 0.8 4.03 73.7 5 90 5 silt 0.19 7.4 38.4 136

12 Plot 12 

(onsite control)0-18”

94 582 4.2 0.7 4.16 70.3 5 90 5 silt 0.11 10.4 36.0 136

13 Plot 11

Duplicate

89 508 4.3 0.7 3.95 72.7 3 92 5 silt 0.08 6.7 36.6 140

Table 4. Cations and other physicochemical results from Montana State University Soil Testing Laboratory. 

Samples collected on July 9, 2003

Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

13

3.0 Research Results

In the first growing season, 2004, response variables, 

including emergence and establishment, density, 

and canopy cover, were evaluated. Concentrations 

of metals in vegetation were evaluated in terms of 

plant sufficiency or excess and in terms of maximum allowable dietary levels for cattle. Changes in 

soil rootzone pH, conductivity, and soluble metal 

concentrations before and after treatment were 

also determined. Results from these data were 

presented by Neuman et al. (2005).

In July 2005, the vegetation growing on the 

12 experimental plots at the Keating tailings pond 

was evaluated. Canopy cover by species within 

each plot was determined using the Daubenmire’s 

cover class method (Daubenmire 1959). Samples 

of aboveground plant material were collected by 

clipping, drying, and weighing. Rooting patterns 

were evaluated by developing excavation pits with 

selected plots. Digital images were collected and 

field notes were written. Samples of dried vegetation were submitted to BLM for determination of 

metal (cadmium, copper, lead, mercury, and zinc) 

and arsenic concentrations.

3.1 General Comments 

Regarding the Site in July 2005

Heavy spring rains in 2005 stimulated excellent 

plant growth on the treated tailings plots (refer 

to Figures A-1 and A-2 in Appendix A). Slender 

wheatgrass (Elymus trachycaulus) and western 

wheatgrass (Pascopyrum smithii) were approximately 

48 inches tall (Figure A-3). All seeded species, 

except American vetch (Vicia americana), were found

on all of the treated plots. The vetch was noticeably 

absent and occurred as an incidental species in 

one treated plot. Several nonseeded plant species 

established in the treated plots. The onsite untreated tailings plots (controls) had sparse vegetation 

(Figure A-4) limited to three of the seeded species: 

western wheatgrass, slender wheatgrass, and big 

bluegrass (Poa ampla). Evidence of rodent activity, 

most likely from meadow voles (Microtus pennsylvanicus) or white-footed deer mice (Peromyscus sp.), 

was present in the treated tailings plots but not on 

the control plots. The offsite plots on native soils 

supported very good plant growth (Figure A-5). 

Many species were present that were not in the 

seed mix, but the plots were dominated by slender 

wheatgrass. Many other native species were also 

present. Yellow sweetclover (Melilotus officinalis)

was prevalent on the surrounding hillsides 

(Figure A-1), but absent from all experimental plots.

3.2 Canopy Cover

Five 20- x 50-cm frames were placed along a diagonal transect on each plot. Cover class for each 

individual species within the frame was recorded. 

Canopy cover of perennial grasses and forbs 

determined in 2004, 2005, and 2006 are exhibited in 

Table 5 and Appendix B. Kruskal-Wallis one-way 

analysis of variance by ranks revealed that the median cover value for perennial grasses growing on 

the control tailings plots in 2004 was significantly 

less than the cover of these species growing on 

the offsite native soil plots and the treated tailings 

plots (Table 5).
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

14

Plots Median Perennial Grass 

Canopy Coverage (%)

Mean Forb Canopy 

Coverage (%)

Mean Shrub and Subshrub 

Canopy Coverage (%)

2004 Data

Treated Tailings 62.5 a1 6.25 a ND

Control Tailings 15.0 b 1.50 b ND

Offsite Soils 62.5 a 2.25 b ND

2005 Data

Treated Tailings 65.0 a 3.0 a 0.0

Control Tailings 10.1 b 0.0 0.0

Offsite Soils 39.0 a 2.6 a 5.0

2006 Data

Treated Tailings 66.6 a 3.1 a 0.0

Control Tailings 11.3 b 0.0 0.0

Offsite Soils 52.8 a 4.3 a 3.9

1 Values followed by same letter in columns are not significantly different (P < 0.05).

Table 5. Comparison of perennial grass and forb canopy cover on the experimental plots.

Mean forb canopy cover measured in 2004 was 

significantly less for the offsite native soils compared 

to the forb cover on the treated tailings plots.

Analysis of variance indicated that the percent 

cover of perennial grasses growing on the treated 

tailings in 2005 is significantly (P < 0.05) greater 

than percent canopy cover of perennial grasses 

growing on the control tailings. Canopy cover of 

vegetation on the treated tailings was not statistically distinct from perennial grasses growing on 

the offsite plots. The percents of canopy cover 

of forbs growing on the treated tailings and the 

offsite plots were also statistically equivalent. This 

same statistical pattern of canopy cover was found 

in 2006.

3.3 Species List

A species list of all plants found within each of the 

12 experimental plots was developed (Table 6). 

Species are distinguished by whether they were 

part of the seed mix or naturally established 

within the plot. The detailed vegetation cover data 

were used to designate major species with a mean 

cover of greater than 0.5 percent for the plot and 

those species that were present during the July 

survey but contributed little to the overall 

vegetation cover of the plot.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

15

Scientific Name Common Name Seeded 

Species

Offsite Native Soils Treated Tailings Untreated Tailings

(Y/N) 1 2 3 4 5 6 9 11 7 8 10 12

Achillea millefolium Common yarrow Y M X M M M M M M X XAchnatherum hymenoides Indian ricegrass Y M M M M X X X M XArtemisia frigida Prairie sagewort Y M M M M X X XArtemisia ludoviciana Cudweed sagewort Y M M M M X X X XArtemisia tridentata Big sagebrush N X X X XAstragalus spp. Milkvetch N MBrassica nigra Black mustard N X XChenopodium berlandieri Pitseed goosefoot N X XChrysothamnus nauseosus Rubber rabbitbrush N XElymus trachycaulus Slender wheatgrass Y M M M M M M M M M M M MFestuca L. Fescue N MGutierrezia sarothrae Broom snakeweed N X X X XHesperostipa comata Needle and thread N M M M M X XHordeum jubatum Foxtail barley N X X M X X X XHordeum L. Barley N X X X X XLepidium densiflorum Common pepperweed N X MNassella viridula Green needlegrass Y M M M M X M M MOpuntia polyacantha Plains pricklypear N M XPascopyrum smithii Western wheatgrass Y M M M M M M M M M M M MPlantago patagonica Woolly plantain N XPoa ampla Big bluegrass Y M M M M M X M M X MPoa spp. Bluegrass N X X XPolygonum aviculare Prostrate knotweed N X X XPolygonum lapathifolium Curlytop knotweed N X X XPopulus tremuloides Quaking aspen N X X X XPotentilla L. Cinquefoil N XSphaeralcea coccinea Scarlet globemallow N M X XTragopogon dubius Yellow salsify N X X XUnknown Ground lichen N XVerbena bracteata Bigbract verbena N XVicia americana American vetch Y X XNumber of Species 13 15 14 18 10 16 15 14 4 6 5 8

Table 6. Species occurring on each experimental plot of the Keating tailings project, 2005.

M = major species with > 0.5% cover, X = other species occurring in the plot. 

Plots 1-4 are offsite native soils; plots 5, 6, 9, and 11 are onsite treated tailings; plots 7, 8, 10, 12 are onsite control.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

16

Figure 4. Mean aboveground biomass.

3.4 Aboveground Biomass

A 25- x 25-cm frame was placed in the same location as the cover frame, and vegetation with each 

frame was clipped, segregated by plant species, 

and placed into separate labeled paper bags for 

transport to the RRU labs. The samples were oven 

dried (70o C) for 24 to 36 hours. The vegetation 

mass in each bag was weighed to the nearest 

0.01 gram. Mean aboveground biomass of live 

vegetation in grams/m2 is displayed in Figure 4. 

Analysis of variance indicated significant differences (P < 0.05) among the three mean values, 

with the treated tailings supporting the greatest 

aboveground plant biomass, followed by the offsite 

native range soils.

0

100

200

300

400

500

600

700

800

Mean Aboveground Biomass (g/m2

)

Offsite Treated

Tailings

Experimental Plot Designations

Untreated

Tailings

471.90

671.43

62.88

The untreated tailings did support some plant 

growth, but it was significantly less than the 

treated tailings and offsite native range soils. Two 

grasses, western wheatgrass and slender wheatgrass contributed most to the biomass on all plots 

and treatments (refer to Appendix C for biomass 

data for each species and plot).

3.5 Metal Levels in Vegetation

Vegetation samples collected for biomass 

determinations were submitted to BLM in Denver 

for determination of concentrations of selected 

elements, including arsenic, cadmium, lead, 

copper, zinc, and mercury. Mean levels of these 

elements in grass samples [western wheatgrass, 

slender wheatgrass, Indian ricegrass (Achnatherum 

hymenoides) and big bluegrass] collected from the 

experimental plots are provided in Figures 5 and 6. 

The complete data set of elemental levels in 

vegetation is provided in Appendix D.

Arsenic in Vegetation

Analysis of variance indicated that the mean 

arsenic level in grasses growing on the untreated 

tailings (2.60 mg/kg) was significantly greater than 

mean concentrations for grasses growing on treated tailings (1.09 mg/kg). Grasses growing on the 

native range soils revealed the least arsenic, with 

a mean of 0.36 mg/kg. For these statistical tests, 

any arsenic value reported at the detection limit 

was multiplied by 0.7, with the resulting value 

used to calculate mean concentrations. Based on a 

review of the scientific literature (Kabata-Pendias 

and Pendias 1992), normal or sufficient levels of 

arsenic in mature leaf tissue range from 1 to 

1.7 mg/kg; excessive or toxic levels for plants range 

from 5 to 20 mg/kg. None of the individual grass 

samples collected from the experimental plots had 

arsenic levels in the excessive range. The maximum 

tolerable dietary level of arsenic for cattle and 

horses (NRC 1980) is 50 mg/kg. The arsenic 

concentrations in grasses growing on the Keating 

tailings do not pose a threat to grazing animals.

Cadmium in Vegetation

The mean concentration of cadmium in samples 

collected from the untreated tailings was 3.23 mg/kg, 

which was not statistically distinct from the mean 

cadmium concentration of grasses collected from 

the treated plots (0.70 mg/kg). A significantly lower 

mean concentration of cadmium was found in 

grasses growing on the native soils (0.04 mg/kg).
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

17

Figure 5. Mean concentrations of arsenic, cadmium, 

and lead in grass samples. Mean Concentration in Grass Tissue (mg/kg)

Element

Arsenic Cadmium Lead

0.0

0.36

0.04

0.5

1.0

1.5

2.0

2.5

3.0

3.5

1.09

0.70

0.12

0.40

1.80

2.60

3.23

offsite

native soils

treated

tailings

untreated

tailings

Copper

Element

Zinc

0

50

2.71

8.95

25.16

9.80

53.38

216.71

100

150

Mean Concentration in Grass Tissue (mg/kg) 200

250

offsite

native soils

treated

tailings

untreated

tailings

The maximum tolerable dietary level of cadmium 

for cattle and horses is 0.50 mg/kg (NRC 1980). 

Of the eight individual grass samples from the 

treated tailings (refer to Appendix D), one sample 

of Indian ricegrass was found to have a cadmium 

concentration of 2.13 mg/kg, while the other 

samples had cadmium concentrations ranging 

from 0.21 to 0.80 mg/kg. The dietary level of 

cadmium for domesticated animals is based on human food residue considerations (NRC 1980) and 

the need to avoid increases of cadmium in the U.S. 

food supply. Higher residue levels (>0.50 mg/kg) 

for a short period of time would not be expected 

to be harmful to animal health or to human food 

use, particularly if the animals were slaughtered at 

a young age (NRC 1980).

Lead in Vegetation

Lead levels in vegetation samples were relatively 

low. Analysis of variance indicated that the mean 

concentration of lead in grasses growing on the 

untreated tailings (1.80 mg/kg) was significantly 

elevated compared to mean levels in grasses growing on the treated tailings (0.40 mg/kg) or native 

range soils (0.12 mg/kg). All concentrations were 

less than the maximum tolerable dietary level for 

cattle and horses of 30 mg/kg (NRC 1980). Normal concentrations of lead in mature leaf tissue 

range from 5 to 10 mg/kg (Kabata-Pendias and 

Pendias 1992). All lead levels were below this range 

(refer to Appendix D). The lead concentrations 

in grasses growing on the Keating tailings do not 

pose a threat to grazing animals.

Copper in Vegetation

Mean concentrations of copper in grass samples 

collected from the site were significantly different 

across the three treatments (Figure 6). The grasses 

growing in offsite native range soils had a mean 

copper level of 2.71 mg/kg. This level would be 

considered in the deficient range for this essential 

element. Mean levels of copper in grasses growing 

on treated and untreated tailings, 8.95 and 

25.16 respectively, are statistically different 

(P < 0.05), but within the sufficient or normal 

range of 5 to 30 mg/kg provided by (KabataPendias and Pendias 1992). The maximum tolerable 

dietary level of copper for cattle and horses is 

Figure 6. Mean concentrations of copper and zinc in 

grass samples.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

18

100 mg/kg (NRC 1980). The copper concentrations 

in grasses growing on the Keating tailings do not 

pose a threat to grazing animals.

Zinc in Vegetation

Mean zinc concentrations were quite variable 

(Figure 6), and analysis of variance found that they 

were statistically distinct. The maximum dietary 

level of zinc for cattle and horses is 500 mg/kg 

(NRC 1980); no sample concentration exceeded 

this value. The zinc concentrations in grasses 

growing on the Keating tailings do not pose a 

threat to grazing animals.

Mercury in Vegetation

All of the mercury values were < 0.1 mg/kg 

(refer to Appendix D). No interpretation of the 

data is necessary.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

19

4.0 Future 

Directions

Phytostabilization takes advantage of soil 

amendments and metals- and acid-tolerant 

plants to revegetate sites. In so doing, metals 

are immobilized, for the most part, and are not 

available for migration or exposure. Proper 

selection of amendments is necessary to ensure 

growth; proper selection of plants is also necessary 

to ensure growth and to prevent bioaccumulation.

The Bridger USDA Natural Resources Conservation Service (NRCS) Plant Materials Center has 

collected and cultivated metals-tolerant plants 

from the Anaconda Superfund site and released 

varieties of basin wild rye, fuzzytongue penstemon,

and common snowberry. The Center plans to 

release additional species for metals-contaminated 

sites, including slender wheatgrass, western 

wheatgrass, bluebunch wheatgrass, big bluegrass, 

silverleaf phacelia, woolly cinquefoil, Woods’ 

rose, silver buffaloberry, western snowberry, and 

horizontal juniper. These native species, along 

with introduced species such as redtop and tufted 

hairgrass should be considered for BLM sites in 

the Rocky Mountain states. Future work should be 

performed to identify metals-tolerant species for 

other BLM states.

Recent field studies by MSU RRU suggest that 

there is an upper threshold on the total toxic 

metals concentration for which phytostabilization 

is effective. Soil amendments can help neutralize 

acidity and precipitate metals to a point, after 

which the technology may be ineffective. Work by 

RRU suggests this threshold can be estimated by 

the following regression equation (Jennings and 

Neuman 2006):

Total Metals [As+Cd+Cu+Pb+Zn] = 520 x pH - 2300

For example, at a pH of 7.0, when the sum of 

metals is greater than 1,340 mg/kg, phytotoxic 

conditions are expected with increasing severity as 

the sum of metals increases above the threshold.

In other recent work, MSU RRU performed soil 

greenhouse toxicity studies to assess the phytotoxicity of actual site soils with metal mixtures 

[As+Cd+Cu+Pb+Zn] to reclamation plants 

(Martin and Neuman 2006). Metals-tolerant 

plants such as slender wheatgrass, basin wildrye, 

and blue bunchgrass were evaluated. Mine waste 

“soils” were neutralized with lime and diluted 

with control soil into various doses. This work 

suggests that biomass is reduced by 50 percent for 

slender wheatgrass at about 3500 mg/kg, for basin 

wildrye at 2600 mg/kg, and for blue bunchgrass 

at 2800 mg/kg. The slope of the dose response 

curve suggests that 10 percent biomass reduction 

is found for these species at 700 mg/kg, 

700 mg/kg, and 900 mg/kg total metals, respectively. However, soil is a complex medium and 

other soil factors such as texture and organic 

matter may affect phytotoxicity. Greenhouse 

studies such as these can help ensure the success 

of reclamation work, especially if other plant 

species are phytostabilization candidates.

For sites with more than about 1,300 mg/kg total 

metals as defined above, capping with topsoil or 

cover soil will be more effective than in situ 

phytostabilization.

Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

21

References Cited

Adriano, D.C. 1986. Trace elements in the terrestrial 

environment. Springer-Verlag, New York. 533 pp.

ASA (American Society of Agronomy). 1986. 

Methods of soil analysis: Part 2-Chemical and 

microbiological methods. 2nd edition. Klute, A. 

(ed). American Society of Agronomy and Soil 

Science Society of America, Madison, WI.

ASA (American Society of Agronomy). 1982. 

Methods of soil analysis. Page et al. (ed). Agronomy Monograph No. 9. SMP Single Buffer 

Method, 12-3.4.4.4. Madison, WI. pp. 215-217.

APHA (American Public Health Association). 

1989. Standard methods for the examination of 

water and wastewater. 17th edition. Clesceri, 

L.S., A.E. Greenberg and R.R. Trussell (eds). 

Washington, DC.

ASTM (American Society for Testing and Materials).

1997. Annual book of ASTM standards. Vol. 4.01 

and 4.08. West Conshohocken, PA.

Daubenmire, R. 1959. A canopy-coverage method 

of vegetational analysis. Northwest Science 

33:43-64.

Ford, K.L and D. Neuman, 2004. Phytostabilization 

of abandoned mine sites. Proceedings of the 

26th Annual National Association of Abandoned 

Mine Land Program Conference, Flagstaff, AZ.

Jennings, S. and D. Neuman. 2006. Phytotoxic 

constraints to vegetation establishment at the 

Anaconda Smelter Superfund site. Billings Land 

Reclamation Symposium, Billings MT.

Kabata-Pendias, A. and H. Pendias. 1992. Trace 

elements in soils and plants. CRC Press, Boca 

Raton, FL. 365 pp.

Martin, T. and D. Neuman. 2006. Differential plant 

response to plants to varying levels of metals 

and arsenic to lime-amended contaminated 

soils. Billings Land Reclamation Symposium, 

Billings, MT.

Munshower, F.F. 1994. Practical handbook of 

disturbed land revegetation. CRC Press, Boca 

Raton, FL. 265 pp.

Neuman, D.R., G.S. Vandeberg, P.B. Blicker, J.D. 

Goering, S.R. Jennings, and K. Ford. 2005. Phytostabilization of acid metalliferous mine tailings 

at the Keating site in Montana. In: Proceedings 

of the 2005 National Meeting of the American 

Society of Mining and Reclamation, Breckenridge, CO. Published by ASMR, 3134 Montavesta 

Road, Lexington, KY 40502.

NRC (National Research Council). 1980. Mineral 

tolerance of domestic animals. National Academy 

of Sciences, Washington, DC. 577 pp.

RRU (Reclamation Research Unit). 2003. Revised 

work plan for phytostabilization studies at the 

Keating tailings site. Prepared by Reclamation 

Research Unit, Montana State University for Karl 

Ford, U.S. Department of the Interior, BLM, 

Denver, CO.

Salt, D.E. et al. 1995. Phytoremediation: A novel 

strategy for the removal of toxic metals from 

the environment using plants. Bio/Technol. 13: 

468-474.

Sobek, A.A., J.G. Skousen, and S.E. Fisher, Jr. 2000. 

Chemical and physical properties of overburden 

and mine soils. In Barnhisel, R.I., R.G. Darmody, 

and W.L. Daniels (eds). Reclamation of drastically disturbed lands. Agronomy Monograph 

No. 41; ASA, CSSA, and SSA; Madison, WI.

Sobek, A.A., W.A. Schuller, J.R. Freeeman, and 

R.M. Smith. 1978. Field and laboratory methods 

applicable to overburdens and mine soils. EPA600/2-78-054. U.S. Environmental Protection 

Agency Technology, Cincinnati, OH. 203 pp.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

22

USEPA (U.S. Environmental Protection Agency) 

and MDEQ (Montana Department of Environmental Quality). 1998. Record of decision. 

Anaconda Regional Water, Waste and Soils 

Operable Unit. Helena, MT.

USEPA (U.S. Environmental Protection Agency). 

2000. Introduction to phytoremediation. 

EPA/600/R-99/107. National Risk Management 

Laboratory. Cincinnati, OH.

U.S. Salinity Laboratory Staff. 1969. Diagnosis and 

improvement of saline and alkali soils. Agricultural Handbook No. 60. U.S. Department of 

Agriculture, Washington, DC. 160 pp.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Appendix A–Site 

Photos from July 

2005

Figure A-1. An overview 

of experimental plots on 

Keating tailings, July 6, 

2005. Note apparent difference between treated 

tailings and untreated 

tailings.

Figure A-2. The treated 

tailings plots.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Figure A-3. A treated plot 

with yarrow in flower 

along the plot edge and 

the stand dominated by 

the seeded wheatgrasses.

Figure A-4. Untreated 

(control) tailings plots.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Figure A-5. Offsite 

experimental plots on 

native soils.

Figure A-6. Treated 

tailings pit face and roots 

sprayed with Hellige pH 

indicator solution. The 

pH of the tailings is 

approximately 7 to 8.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

26

Figure A-7. Untreated 

(control) tailings pit face 

and roots sprayed with 

Hellige pH indicator 

solution. The pH of the 

tailings is approximately 

4.5.
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Appendix B–Canopy 

Cover of Vegetation
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Table B-1. Vegetation cover at Keating tailings, July 7, 2005. Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean Cover Class Percent Class Percent Class Percent Class Percent Class Percent per Plot Perennial Grasses Hesperostipa comata 1 2.5 1 2.5 1.0 Poa ampla 1 2.5 1 2.5 1 2.5 1.5 Pascopyrum smithii 1 2.5 2 15.0 1 2.5 1 2.5 1 2.5 5.0 Elymus trachycaulus 2 15.0 3 37.5 2 15.0 3 37.5 3 37.5 28.5 Nassella viridula 1 2.5 0.5 Achnatherum hymenoides 1 2.5 0.5 Total Perennial Grasses 22.5 55.0 20.0 42.5 45.0 37.0 Perennial Forbs Artemisia ludoviciana 1 2.5 1 2.5 1.0 Achillea millefolium 1 2.5 0.5 Total Perennial Forbs 0.0 5.0 2.5 0.0 0.0 1.5 Shrubs and Subshrubs Artemisia frigida 2 15.0 1 2.5 2 15.0 1 2.5 7.0

Opuntia polyacantha 1 2.5 0.5Total Shrubs and Subshrubs 17.5 2.5 15.0 2.5 0.0 7.5Sum of Species Cover 40.0 62.5 37.5 45.0 45.0 46.0Total Live Vegetation Cover 40.0 62.5 37.5 45.0 45.0 46.0Litter 1 2.5 2 15.0 2 15.0 2 15.0 2 15.0 12.5Mulch 1 2.5 1 2.5 3 37.5 2 15.0 3 37.5 19.0Bare ground 2 15.0 1 2.5 1 2.5 1 2.5 1 2.5 5.0Total Ground Cover 45.0 80.0 90.0 75.0 97.5 77.5

PLOT 1 - Offsite Native Range Site
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Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean Cover

Class Percent Class Percent Class Percent Class Percent Class Percent per Plot

Perennial GrassesHesperostipa comata 1 2.5 1 2.5 1.0Poa ampla 1 2.5 1 2.5 1.0Pascopyrum smithii 1 2.5 1 2.5 1 2.5 1 2.5 1 2.5 2.5Elymus trachycaulus 3 37.5 3 37.5 2 15.0 3 37.5 2 15.0 28.5Nassella viridula 1 2.5 0.5Achnatherum hymenoides 1 2.5 1 2.5 1 2.5 1.5Total Perennial Grasses 40.0 45.0 25.0 40.0 25.0 35.0Perennial ForbsArtemisia ludoviciana 1 2.5 2 15.0 1 2.5 4.0Total Perennial Forbs 2.5 15.0 2.5 0.0 0.0 4.0Shrubs and SubshrubsArtemisia frigida 1 2.5 2 15.0 2 15.0 6.5Sphaeralcea coccinea 1 2.5 0.5Total Shrubs and Subshrubs 2.5 15.0 0.0 2.5 15.0 7.0Sum of Species Cover 45.0 75.0 27.5 42.5 40.0 46.0Total Live Vegetation Cover 45.0 75.0 27.5 42.5 40.0 46.0Litter 2 15.0 2 15.0 2 15.0 2 15.0 1 2.5 12.5Mulch 2 15.0 2 15.0 2 15.0 3 37.5 2 15.0 19.5Bare ground 1 2.5 1 2.5 0 0 2 15.0 4.0Total Ground Cover 75.0 105.0 57.5 95.0 57.5 78.0

Table B-2. Vegetation cover at Keating tailings, July 7, 2005. PLOT 2 – Offsite Native Range Site
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Table B-3. Vegetation cover at Keating tailings, July 7, 2005. Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean Cover Class Percent Class Percent Class Percent Class Percent Class Percent per Plot Perennial Grasses Hesperostipa comata 1 2.5 1 2.5 1.0 Pascopyrum smithii 1 2.5 1 2.5 2 15.0 1 2.5 1 2.5 5.0 Elymus trachycaulus 2 15.0 3 37.5 4 62.5 3 37.5 2 15.0 33.5 Nassella viridula 1 2.5 0.5 Achnatherum hymenoides 1 2.5 0.5 Festuca L. 1 2.5 0.5 Total Perennial Grasses 25.0 45.0 77.5 40.0 17.5 41.0 Annual Grasses Hordeum L. 1 2.5 0.5 Total Annual Grasses 0.0 2.5 0.0 0.0 0.0 0.5 Perennial Forbs Artemisia ludoviciana 1 2.5 1 2.5 1 2.5 1.5 Achillea millefolium 1 2.5 0.5

Total Perennial Forbs 2.5 0.0 0.0 5.0 2.5 2.0Shrubs and SubshrubsArtemisia frigida 1 2.5 1 2.5 1.0Total Shrubs and Subshrubs 2.5 0.0 0.0 0.0 2.5 1.0Sum of Species Cover 30.0 47.5 77.5 45.0 22.5 44.5Total Live Vegetation Cover 30.0 47.5 77.5 45.0 22.5 44.5Litter 1 2.5 2 15.0 2 15.0 2 15.0 1 2.5 10.0Mulch 1 2.5 2 15.0 2 15.0 2 15.0 2 15.0 12.5Bare ground 3 37.5 1 2.5 0 1 2.5 3 37.5 16.0Total Ground Cover 35.0 77.5 107.5 75.0 40.0 67.0

PLOT 3 - Offsite Native Range Site
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Table B-4. Vegetation cover at Keating tailings, July 7, 2005. Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean cover Class Percent Class Percent Class Percent Class Percent Class Percent per plot Perennial Grasses Hesperostipa comata 1 2.5 1 2.5 1.0 Poa ampla 1 2.5 2 15.0 1 2.5 1 2.5 4.5 Pascopyrum smithii 2 15.0 1 2.5 1 2.5 2 15.0 1 2.5 7.5 Elymus trachycaulus 3 37.5 2 15.0 3 37.5 3 37.5 2 15.0 28.5 Nassella viridula 1 2.5 1 2.5 1.0 Achnatherum hymenoides 1 2.5 1 2.5 1.0 Hordeum jubatum 1 2.5 0.5 Total Perennial Grasses 57.5 37.5 50.0 52.5 22.5 44.0 Perennial Forbs Artemisia ludoviciana 1 2.5 1 2.5 1 2.5 1.5 Achillea millefolium 1 2.5 0.5 Lepidium densiflorum 1 2.5 0.5 Astragalus spp. 1 2.5 0.5

Total Perennial Forbs 2.5 2.5 5.0 2.5 2.5 3.0Shrubs and SubshrubsArtemisia frigida 1 2.5 1 2.5 1 2.5 2 15.0 4.5

Total Shrubs and Subshrubs 2.5 2.5 2.5 0.0 15.0 4.5

Sum of Species Cover 62.5 42.5 57.5 55.0 40.0 51.5Total Live Vegetation Cover 62.5 42.5 57.5 55.0 40.0 51.5Litter 2 15.0 2 15.0 2 15.0 2 15.0 2 15.0 15.0Mulch 2 15.0 2 15.0 2 15.0 2 15.0 3 37.5 19.5Bare ground 2 15.0 1 2.5 1 2.5 1 2.5 1 2.5 5.0Total Ground Cover 92.5 72.5 87.5 85.0 92.5 86.0

PLOT 4 – Offsite Native Range Site
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Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean Cover

Class Percent Class Percent Class Percent Class Percent Class Percent per plot

Perennial GrassesPoa ampla 1 2.5 0.5Pascopyrum smithii 3 37.5 1 2.5 1 2.5 2 15.0 3 37.5 19.0Elymus trachycaulus 3 37.5 4 62.5 1 2.5 2 15.0 3 37.5 31.0Total Perennial Grasses 75.0 65.0 5.0 30.0 77.5 50.5Perennial ForbsAchillea millefolium 1 2.5 2 15.0 3.5Total Perennial Forbs 0.0 2.5 0.0 0.0 15.0 3.5Shrubs and SubshrubsTotal Shrubs and Subshrubs 0.0 0.0 0.0 0.0 0.0 0.0Sum of Species Cover 75.0 67.5 5.0 30.0 92.5 54.0Total Live Vegetation Cover 75.0 67.5 5.0 30.0 92.5 54.0Litter 2 15.0 2 15.0 4 62.5 2 15.0 2 15.0 24.5Mulch 0 0 0 1 2.5 1 2.5 1.0Bare ground 2 15.0 2 15.0 1 2.5 2 15.0 1 2.5 10.0Total Ground Cover 90.0 82.5 67.5 47.5 110.0 79.5

Table B-5. Vegetation cover at Keating tailings, July 7, 2005. PLOT 5 - Onsite Treated with Lime and Organic Matter
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Table B-6. Vegetation cover at Keating tailings, July 7, 2005. Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean Cover Class Percent Class Percent Class Percent Class Percent Class Percent per Plot Perennial Grasses Poa ampla 1 2.5 0.5 Pascopyrum smithii 2 15.0 2 15.0 1 2.5 2 15.0 1 2.5 10.0 Elymus trachycaulus 4 62.5 4 62.5 4 62.5 4 62.5 4 62.5 62.5 Nassella viridula 1 2.5 1 2.5 1.0 Total Perennial Grasses 77.5 80.0 65.0 77.5 70.0 74.0 Perennial Forbs Achillea millefolium 1 2.5 2 15.0 2 15.0 1 2.5 7.0 Total Perennial Forbs 0.0 2.5 15.0 15.0 2.5 7.0 Shrubs and Subshrubs Total Shrubs and Subshrubs 0.0 0.0 0.0 0.0 0.0 0.0 Sum of Species Cover 77.5 82.5 80.0 92.5 72.5 81.0 Total Live Vegetation Cover 77.5 82.5 80.0 92.5 72.5 81.0 Litter 2 15.0 2 15.0 2 15.0 2 15.0 2 15.0 15.0

Mulch 1 2.5 1 2.5 1 2.5 1 2.5 1 2.5 2.5Bare ground 0 0 0 0 0 0.0Total Ground Cover 95.0 100.0 97.5 110.0 90.0 98.5

PLOT 6 - Onsite Treated with Lime and Organic Matter
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean cover

Class Percent Class Percent Class Percent Class Percent Class Percent per plot

Perennial GrassesPoa ampla 1 2.5 0.5Pascopyrum smithii 1 2.5 1 2.5 1 2.5 1 2.5 2.0Elymus trachycaulus 1 2.5 1 2.5 1 2.5 1 2.5 1 2.5 2.5Total Perennial Grasses 5.0 5.0 7.5 5.0 2.5 5.0Perennial ForbsTotal Perennial Forbs 0.0 0.0 0.0 0.0 0.0 0.0Shrubs and SubshrubsTotal Shrubs and Subshrubs 0.0 0.0 0.0 0.0 0.0 0.0Sum of Species Cover 5.0 5.0 7.5 5.0 2.5 5.0Total Live Vegetation Cover 5.0 5.0 7.5 5.0 2.5 5.0Litter 0 0 0 0 0 0 0Mulch 4 62.5 3 37.5 3 37.5 3 37.5 4 62.5 47.5Bare ground 2 15.0 4 62.5 3 37.5 3 37.5 2 15.0 33.5Total Ground Cover 67.5 42.5 45.0 42.5 65.0 52.5

Table B-7. Vegetation cover at Keating tailings, July 7, 2005. PLOT 7 - Onsite Control
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Table B-8. Vegetation cover at Keating tailings, July 7, 2005. Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean cover Class Percent Class Percent Class Percent Class Percent Class Percent per plot Perennial Grasses Poa ampla 2 15.0 1 2.5 1 2.5 2 15.0 7.0 Pascopyrum smithii 1 2.5 1 2.5 1 2.5 1 2.5 1 2.5 2.5 Elymus trachycaulus 1 2.5 2 2 15.0 1 2.5 4.0 Total Perennial Grasses 20.0 5.0 20.0 20.0 2.5 13.5 Perennial Forbs Total Perennial Forbs 0.0 0.0 0.0 0.0 0.0 0.0 Shrubs and Subshrubs Total Shrubs and Subshrubs 0.0 0.0 0.0 0.0 0.0 0.0 Trees Populus tremuloides 1 2.5 0.5 Total Trees 0.0 2.5 0.0 0.0 0.0 0.5 Sum of Species Cover 20.0 7.5 20.0 20.0 2.5 14.0 Total Live Vegetation Cover 20.0 7.5 20.0 20.0 2.5 14.0

Litter 0 0 0 0 0 0.0Mulch 3 37.5 3 37.5 2 15.0 3 37.5 2 15.0 28.5Bare ground 1 2.5 2 15.0 3 37.5 2 15.0 5 85.0 31.0Total Ground Cover 57.5 45.0 35.0 57.5 17.5 42.5

PLOT 8 - Onsite Control
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Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean Cover

Class Percent Class Percent Class Percent Class Percent Class Percent per Plot

Perennial GrassesPoa ampla 1 2.5 0.5Pascopyrum smithii 3 37.5 1 2.5 1 2.5 2 15.0 3 37.5 19.0

Elymus trachycaulus 4 62.5 3 37.5 3 37.5 3 37.5 4 62.5 47.5Nassella viridula 1 2.5 0.5Total Perennial Grasses 102.5 40.0 40.0 52.5 102.5 67.5Perennial ForbsAchillea millefolium 1 2.5 0.5Total Perennial Forbs 0.0 0.0 0.0 0.0 2.5 0.5Shrubs and SubshrubsTotal Shrubs and Subshrubs 0.0 0.0 0.0 0.0 0.0 0.0Sum of Species Cover 102.5 40.0 40.0 52.5 105.0 68.0Total Live Vegetation Cover 102.5 40.0 40.0 52.5 105.0 68.0Litter 2 15.0 2 15.0 3 37.5 2 15.0 2 15.0 19.5Mulch 0 0 3 37.5 2 15.0 1 2.5 1 2.5 11.5Bare ground 0 0 1 2.5 1 2.5 1 2.5 1 2.5 2.0Total Ground Cover 117.5 92.5 92.5 70.0 122.5 99.0

Table B-9. Vegetation cover at Keating tailings, July 7, 2005. PLOT 9 - Onsite Treated with Lime and Organic Matter
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Table B-10. Vegetation cover at Keating tailings, July 7, 2005. Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean Cover Class Percent Class Percent Class Percent Class Percent Class Percent per Plot Perennial Grasses Pascopyrum smithii 2 15.0 1 2.5 1 2.5 4.0 Elymus trachycaulus 2 15.0 2 15.0 1 2.5 1 2.5 1 2.5 7.5 Total Perennial Grasses 30.0 17.5 2.5 5.0 2.5 11.5 Perennial Forbs Total Perennial Forbs 0.0 0.0 0.0 0.0 0.0 0.0 Shrubs and Subshrubs Total Shrubs and Subshrubs 0.0 0.0 0.0 0.0 0.0 0.0 Sum of Species Cover 30.0 17.5 2.5 5.0 2.5 11.5 Total Live Vegetation Cover 30.0 17.5 2.5 5.0 2.5 11.5 Litter 0 0 0 0 0 Mulch 2 15.0 4 62.5 3 37.5 3 37.5 5 85.0 47.5 Bare ground 2 15.0 1 2.5 4 62.5 2 15.0 1 2.5 19.5 Total Ground Cover 45.0 80.0 40.0 42.5 87.5 59.0 PLOT 10 - Onsite Control
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Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean Cover

Class Percent Class Percent Class Percent Class Percent Class Percent per Plot

Perennial GrassesPascopyrum smithii 2 15.0 2 15.0 1 2.5 1 2.5 3 37.5 14.5Elymus trachycaulus 4 62.5 4 62.5 2 15.0 4 62.5 4 62.5 53.0Nassella viridula 1 2.5 0.5Achnatherum hymenoides 1 2.5 0.5Total Perennial Grasses 77.5 77.5 17.5 67.5 102.5 68.5Perennial ForbsAchillea millefolium 1 2.5 1 2.5 1.0Total Perennial Forbs 0.0 0.0 2.5 2.5 0.0 1.0Shrubs and SubshrubsTotal Shrubs and Subshrubs 0.0 0.0 0.0 0.0 0.0 0.0Sum of Species Cover 77.5 77.5 20.0 70.0 102.5 69.5Total Live Vegetation Cover 77.5 77.5 20.0 70.0 102.5 69.5Litter 2 15.0 2 15.0 2 15.0 2 15.0 2 15.0 15.0Mulch 1 2.5 1 2.5 4 62.5 2 15.0 1 2.5 17.0Bare ground 0 0 1 2.5 1 2.5 0 0.0 1.0Total Ground Cover 95.0 95.0 97.5 100.0 120.0 101.5

Table B-11. Vegetation cover at Keating tailings, July 7, 2005. PLOT 11 - Onsite Treated with Lime and Organic Matter
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Life Form and Species Frame 1 Midpoint Frame 2 Midpoint Frame 3 Midpoint Frame 4 Midpoint Frame 5 Midpoint Mean Cover

Class Percent Class Percent Class Percent Class Percent Class Percent per Plot

Perennial GrassesPoa ampla 1 2.5 0.5Pascopyrum smithii 1 2.5 1 2.5 1 2.5 1 2.5 1 2.5 2.5Elymus trachycaulus 2 15.0 2 15.0 1 2.5 1 2.5 1 2.5 7.5Total Perennial Grasses 20.0 17.5 5.0 5.0 5.0 10.5Annual GrassesHordeum L. 1 2.5 0.5Total Annual Grasses 0.0 0.0 2.5 0.0 0.0 0.5Perennial ForbsTotal Perennial Forbs 0.0 0.0 0.0 0.0 0.0 0.0Shrubs and SubshrubsTotal Shrubs and Subshrubs 0.0 0.0 0.0 0.0 0.0 0.0Sum of Species Cover 20.0 17.5 7.5 5.0 5.0 11.0Total Live Vegetation Cover 20.0 17.5 7.5 5.0 5.0 11.0Litter 0 0 0 0 0Mulch 3 37.5 2 15.0 5 85.0 3 37.5 5 85.0 52.0Bare ground 3 37.5 3 37.5 1 2.5 2 15.0 2 15.0 21.5Total Ground Cover 57.5 32.5 92.5 42.5 90.0 63.0

Table B-12. Vegetation cover at Keating tailings, July 7, 2005. PLOT 12 - Onsite Control

Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

41

Appendix C–

Aboveground 

Biomass
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

42

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Mean biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Achillea millefolium 0.03 0.03

Pascopyrum smithii 2.34 1.52 2.77 6.63

Elymus trachycaulus 12.46 34.48 28.06 18.40 40.85 134.25

Artemisia frigida 1.00 1.00

Artemisia ludoviciana 0.52 0.52

Opuntia polyacantha 0.39 0.39

Poa ampla 0.73 3.66 4.39

Hesperostipa comata 2.07 0.39 2.46

Nassella viridula 3.74 2.37 0.77 6.88

500.96

Table C-1. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

PLOT 1 - Offsite Native Range Site (Frame size is 25 cm x 25 cm)

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Mean biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Achillea millefolium 0.07 0.07

Achnatherum 

hymenoides

0.86 0.86

Pascopyrum smithii 2.66 6.10 3.45 3.36 3.75 19.32

Elymus trachycaulus 23.09 25.00 24.37 25.40 5.10 102.96

Artemisia frigida 0.29 0.72 0.76 1.77

Artemisia ludoviciana 0.43 0.37 0.80

Poa ampla 0.61 2.38 2.99

Hesperostipa comata 0.45 7.00 7.45

Nassella viridula 0.92 2.57 3.49

447.07

Table C-2. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

Plot 2 - Offsite Native Range Site (Frame size is 25 cm x 25 cm)
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

43

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Total biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Pascopyrum smithii 2.61 5.06 5.05 2.19 2.89 17.80

Elymus trachycaulus 13.03 31.59 38.39 42.88 7.48 133.37

Artemisia frigida 0.49 3.48 3.97

Artemisia ludoviciana 0.82 0.82

Festuca L. 0.25 0.25

Nassella viridula 2.23 2.23

505.60

Table C-3. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

Plot 3 - Offsite Native Range Site (Frame size is 25 cm x 25 cm)

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Total biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Achillea millefolium 0.12 0.12

Pascopyrum smithii 3.37 3.76 9.48 1.89 18.50

Elymus trachycaulus 11.56 27.71 6.72 19.58 36.15 101.72

Artemisia frigida 0.46 0.84 1.30

Artemisia ludoviciana 0.12 0.12

Poa ampla 6.46 1.19 7.65

Hesperostipa comata 2.36 2.36

Nassella viridula 2.56 1.28 3.84

433.95

Table C-4. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

Plot 4 - Offsite Native Range Site (Frame size is 25 cm x 25 cm)

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Total biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Achillea millefolium 0.20 0.20

Pascopyrum smithii 10.23 0.76 5.47 16.46

Elymus trachycaulus 49.27 61.11 12.45 29.17 43.05 195.05

Hordeum jubatum 1.01 1.01

Nassella viridula 0.46 0.92 0.43 1.81

686.50

Table C-5. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

PLOT 5 - Onsite Treated with Lime and Organic Matter (Frame size is 25 cm x 25 cm)
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Table C-6. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

PLOT 6 - Onsite Treated with Lime and Organic Matter (Frame size is 25 cm x 25 cm)

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Total biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Achillea millefolium 3.25 1.00 4.25

Pascopyrum smithii 4.49 7.68 3.67 2.05 17.89

Elymus trachycaulus 55.78 22.59 3.92 28.56 79.49 190.34

Artemisia ludoviciana 3.14 3.14

Poa ampla 1.55 1.55

694.94

Table C-7. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

PLOT 7 - Onsite Control (Frame size is 25 cm x 25 cm)

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Total biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Pascopyrum smithii 0.94 0.15 1.06 0.64 0.34 3.13

Elymus trachycaulus 0.71 1.7 1.39 3.80

22.18

Table C-8. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

PLOT 8 - Onsite Control (Frame size is 25 cm x 25 cm)

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Total biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Pascopyrum smithii 3.33 2.35 1.00 3.06 0.32 10.06

Elymus trachycaulus 1.84 5.36 2.08 4.09 13.37

Poa ampla 3.74 3.18 1.18 8.10

Populus tremuloides 0.17 0.17

101.44

Table C-9. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

PLOT 9 - Onsite Treated with Lime and Organic Matter (Frame size is 25 cm x 25 cm)

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Total biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Pascopyrum smithii 0.45 7.96 1.56 2.92 12.89

Elymus trachycaulus 76.19 13.51 15.51 21.86 36.70 163.77

Nassella viridula 3.30 3.30

575.81
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Table C-10. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

PLOT 10 - Onsite Control (Frame size is 25 cm x 25 cm)

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Total biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Pascopyrum smithii 1.74 1.65 2.13 0.40 0.33 6.25

Elymus trachycaulus 12.45 2.45 0.60 15.50

Poa ampla 1.28 1.28

73.70

Table C-11. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

PLOT 11 - Onsite Treated with Lime and Organic Matter (Frame size is 25 cm x 25 cm)

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Total biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Achillea millefolium 0.17 1.58 1.75

Achnatherum 

hymenoides

2.24 2.24

Pascopyrum smithii 4.20 2.93 1.55 15.38 6.39 30.45

Elymus trachycaulus 25.12 42.82 10.55 71.16 42.37 192.02

Poa ampla 1.19 1.19

728.48

Table C-12. Aboveground biomass vegetation at Keating tailings, July 7, 2005.

PLOT 12 - Onsite Control (Frame size is 25 cm x 25 cm)

Species Frame 1 Frame 2 Frame 3 Frame 4 Frame 5 Total biomass

(g) (g) (g) (g) (g) (g/m2) per plot

Pascopyrum smithii 0.59 2.41 2.08 0.09 0.60 5.77

Elymus trachycaulus 0.89 5.18 2.26 2.26 0.54 11.13

Astragalus spp. 0.03 0.03

54.18

Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

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Appendix D–Arsenic 

and Metal Levels in 

Vegetation
Phytostabilization as a Remediation Alternative at Mining Sites TECHNICAL NOTE 420

48

Arsenic Cadmium Lead Copper Zinc Mercury

Offsite Control

VEG1 Western wheatgrass 0.4 <0.05 0.20 3.0 11 <0.1

VEG2 Western wheatgrass 0.3 <0.05 0.11 2.8 11 <0.1

VEG3 Western wheatgrass <0.3 <0.05 0.06 2.5 12 <0.1

VEG4 Western wheatgrass <0.3 <0.05 0.07 2.5 11 <0.1

VEG 13 Slender wheatgrass <0.3 <0.05 <0.11 2.5 9 <0.1

VEG 14 Slender wheatgrass <0.3 <0.05 0.21 2.6 10 <0.1

VEG 15 Slender wheatgrass <0.3 <0.05 0.08 2.1 9 <0.1

VEG 16 Slender wheatgrass <0.3 <0.05 0.06 2.2 7 <0.1

VEG 30 Big bluegrass 0.7 <0.05 0.23 3.4 9 <0.1

VEG 31 Big bluegrass 0.8 0.05 0.14 3.5 9 <0.1

VEG 39 Fringed sagewort 7.8 1.32 9.20 19.0 57 <0.1

Treated Tailings

VEG5 Western wheatgrass 3.3 0.21 0.47 7.8 34 <0.1

VEG9 Western wheatgrass 0.6 0.80 0.81 11.4 84 <0.1

VEG11 Western wheatgrass 0.3 0.66 0.09 8.1 71 <0.1

VEG 17 Slender wheatgrass 0.9 0.28 0.30 6.1 24 <0.1

VEG 18 Slender wheatgrass 0.7 0.55 0.37 8.8 47 <0.1

VEG 21 Slender wheatgrass 0.8 0.34 0.25 10.1 56 <0.1

VEG 23 Slender wheatgrass 1.3 0.66 0.65 8.9 67 <0.1

VEG 41 Indian ricegrass 0.8 2.13 0.23 10.4 44 <0.1

VEG 40 Cudweed sagewort 2.6 3.62 1.62 27.5 69 <0.1

Untreated Tailings

VEG7 Western wheatgrass 3.8 5.01 2.75 40.7 319 <0.1

VEG8 Western wheatgrass 1.8 3.30 1.26 16.5 201 <0.1

VEG 12 Western wheatgrass 2.9 1.98 1.86 23.1 129 <0.1

VEG 19 Slender wheatgrass 2.7 4.14 2.00 26.9 289 <0.1

VEG 20 Slender wheatgrass 3.3 3.64 2.33 26.7 240 <0.1

VEG 22 Slender wheatgrass 1.6 2.66 1.16 22.2 176 <0.1

VEG 34 Big bluegrass 2.1 1.87 1.25 20.0 163 <0.1

Table D-1. Arsenic and metal levels (mg/kg) in vegetation collected from experimental plots at 

Keating tailings, July 7, 2005.
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recommendation for use by the Federal Government.